Adds details on Charara, new law, Szubin quote, effect of the sanctions)

WASHINGTON, Jan 7 (Reuters) – The United States imposed sanctions on Thursday on Lebanese financier Ali Youssef Charara and his telecommunications company for providing support to Hezbollah, the first such designations made under a law signed by President Barack Obama last month.

Charara serves as chairman and general manager of Beirut-based Spectrum Investment Group Holding SAL, which provides telecommunications services in the Middle East, Africa and Europe, the U.S. Treasury Department said.

He has received millions of dollars from Hezbollah to invest in commercial projects that financially support the group, the department said in a statement.

The U.S. action freezes Charara’s and his company’s assets that are in the United States or in the control of Americans, and prohibits Americans from engaging in transactions with them.

Hezbollah, the Shi’ite Islamist political and military group backed by Syria and Iran that wields considerable power in Lebanon, has long been designated as a terrorist organization by the United States.

The new U.S. law, called the Hezbollah International Financing Prevention Act of 2015, strengthened U.S. authorities’ ability to target Hezbollah and threatened consequences for those who help the group, the Treasury Department said.

"Hezbollah relies upon accomplices in the business community to place, manage and launder its terrorist funds," said Adam Szubin, acting treasury under secretary for terrorism and financial intelligence.

"We are committed to exposing and disrupting these networks to pressure Hezbollah’s finances and degrade its ability to foment violence in Lebanon, Syria and across the region," Szubin said in a statement.

(Reporting by Doina Chiacu and Yeganeh Torbati; Editing by Will Dunham)